Clean work station

ABSTRACT

A laminar flow clean work station adapted for rapid change in work setup by utilizing a common exhaust plenum and drain and interchangeable work modules. Each module empties separately into the common exhaust plenum and drain. Each module has a separate exhaust damper which is adjustable to suit the particular exhaust requirement of the work to be undertaken at the module. Air is exhausted through the series of apertures formed in each module below a work receiving opening the station work surface. The opening forms a lip overhanging the module work receiving space and has a depending flange to further baffle the apertures from the station work surface.

[ Feb. 13, 1973 1 CLEAN WORK STATION [75] Inventors: Francis Kelso, LosAngeles; Arnold J. Gustin, Glendale, both of Calif.

[73] Assignee: Integrated Air Systems, Inc., Burbank, Calif.

[22] Filed: May 28, 1971 [21] App1.No.: 147,774

[52] US. Cl. ..98/ll5 LH, 55/467, 55/DIG. 29, 23/259, 312/239 [51] Int.Cl.'. ..F23j 11/00 [58] Field of Search.98/42, 115 LH, 115 R; 312/239;55/467, DIG. 29, DIG. 18; 23/259 Primary Examiner-William E. WarnerAssistant Examiner-William E. Tapolcai, Jr. Attorney-Robert R. Thornton[5 7 ABSTRACT A laminar flow clean work station adapted for rapid changein work setup by utilizing a common exhaust plenum and drain andinterchangeable work modules. Each module empties separately into thecommon exhaust plenum and drain. Each module has a separate exhaustdamper which is adjustable to suit the particular exhaust requirement ofthe work to be undertaken at the module. Air is exhausted through theseries of apertures formed in each module below a work receiving openingthe station work surface. The opening forms a lip overhanging the modulework receiving space and has a depending flange to further baffle theapertures from the station work surface.

9 Claims, 9 Drawing Figures CLEAN WORK STATION FIELD OF THE INVENTIONThis invention pertains to a clean work station, i.e., a work bench orsimilar working enclosure characterized by having its own filtered airor gas supply.

DESCRIPTION OF THE PRIOR ART Clean work stations are well known in theprior art, and are the subject of Federal Standard Number 209a datedAug. 10, 1966. Clean work stations may be divided generally intononlaminar flow types and laminar flow types. Laminar flow refers to anair flow in which the entire body of air within the contained area moveswith uniform velocity along parallel flow lines. Thus, a laminar airflow clean work station is a work station in which the laminar air flowcharacteristics predominate throughout the air space, with a minimum ofeddies. Laminar flow clean work stations may fall into one of twogeneral classifications, that in which air flow is horizontal andexhaust is directly out of the work station into the surroundingatmosphere, such as is shown in FIG. 7 of Federal Standard Number 2090and that in which the air flow is vertical and is exhausted through thework surface by means of the application of a vacuum, such as is shownin FIG. 8 of the aforesaid Federal Standard.

For certain applications, such as the boiling of concentrated acids,processes using noxious gasses, and the like, neither of the generallayouts for clean work stations shown in FIG. 7 or FIG. 8 of theaforesaid Federal Standard are practical, since in both instances atleast part of the clean air exhausts directly into the surroundingatmosphere. In such an embodiment, the objectionable gas would becarried into the surrounding atmosphere, causing discomfort, if notinjury, to workers in the area. Therefore, it has become the practicewhen dealing with such substances, to utilize vertical laminar flowclean work stations with increased exhaust capacity, so that air isdrawn from the surrounding atmosphere through the work area into theexhaust system of the work station. Thus, the passage of theobjectionable gasses into the surrounding atmosphere is avoided.However, the exhaust capacity of the work station must be increased inorder to insure an excess of exhaust capacity over clean air input.

In an effort to reduce the exhaust capacity required in suchembodiments, the total surface area to be exhausted has been reduced byvarious methods. For example, rather than exhausting across the entiresurface, a solid work area may be used with a perimetrical exhaustinlet. This inlet may completely surround the work area in someembodiments, and in other embodiments, the exhaust may be taken at thefront and back of the work area, with the intermediate portion being asolid surface upon which the work is accomplished. In either of theseprior art embodiments, the exhaust vacuum is applied equally about theentire work area, without regard to the particular type of work beingcarried on at any one location and the actual quantity of air requiredto be exhausted in order to avoid atmospheric contamination by materialin that location.

A further disadvantage of prior art laminar flow clean work stations hasbeen their lack of flexibility. It has been the practice in the priorart to design and construct such a work station for a given workcapability or operation. If the work capability or operation of thestation is to be changed by reason of a change in manufacturing processor the like, it has been necessary to remove the work station andinstall a different work station specifically constructed for the newprocess or operation. This has been the case even as to work stationsavailable as component part subassemblies. In such devices, the workarea itself has not been capable of being rapidly changed inconfiguration to adapt to different process requirements. Rather, anentirely new work surface has been required which would contain thenecessary utilities and facilities to carry out the particular workdesired.

SUMMARY According to the present invention, the work area of a laminarflow clean work station is divided into separate subcomponents ormodules which are detachably mounted to a work station frame. The workmodules have a generally flat upper surface with a work receivingopening formed therein, a hollow interior, a module exhaust plenumconnected to the hollow interior, and an adjustable damper control forthe module exhaust plenum. The work station frame has a common exhaustplenum into which the module exhaust plenums empty, so that the moduledamper control controls the flow of air from the hollow interior of eachwork module to the common exhaust plenum. Each work module has a wallformed within the module below and recessed from the periphery of thework receiving opening, so that the opening forms an overhanging lipabout the wall. A plurality of apertures are formed within the wall anddisposed in horizontal alignment immediately below the overhanging lip.In the preferred embodiment, the overhanging lip has a depending flangewhich functions to further baffle the apertures from the work surface.By such a structure, the individual requirements, as to exhaust, foreach of the various modules and the work operations being conductedthereon, are individually adjusted and controlled. By utilizing amodular structure in which the modules are readily detachable andinterchangeable, so that a given work station frame may be utilized fora variety of work operations by the simple interchange of appropriatemodules and corresponding adjustment of the module damper controls.

BRIEF DESCRIPTION OF THE DRAWING Referring now to the drawing,

FIG. 1 shows a clean work bench or work station according to the presentinvention;

FIG. 2 shows the work frame of the work station of FIG. 1, together withthe clean air supply;

FIG. 3 shows the work module support frame, upon which the work modulesare mounted, with one work module illustrated as removed from the frame;

FIG. 4 is a detailed view of a portion of the work frame of FIG. 2,illustrating the utility supply and exhaust system;

FIG. 5 is a view of the'clean air supply system for the work station.

FIG. 6 is a view of a work module as installed in the work frame;

FIG. 7 is a view, in section, of the work module of FIG. 6;

FIG. 8 is a view of the work module of FIG. 7 taken along lines 8-8thereof; and

FIG. 9 is a view, in section, of another embodiment of a work module,designed for a different operation or process.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, thereis shown a clean work station or bench 10 of the laminar flow type. Thework station or bench 10 has a frame 12 which carries an air supply unit14. The air supply unit includes one or more blowers (not shown, seeFIG. which draw air from the atmosphere surrounding the work stationthrough prefilters 16. The prefilters 16 may be, for example, one-halfinch thick polyurethane foam which is 63.8 percent or more effective onatmospheric dust by the standard Filter Institute test. Disposed belowthe air supply unit 14 is a work area which contains a series of workmodules 18, 20, 22, 24, 26, 28, supported from a module stand 32 andfrom the station frame 12, as will be explained hereinafter with respectto FIGS. 6, 7, 8 and 9. As will be apparent from FIG. 1, each of thework modules 18, 20, 22, 24, 26, 28, 30 is designed for utilization in adifferent process or to accomplish a different type of work. Whereappropriate, an actual work module may have substituted for it a blankwork module. At the rear of the work station 10 an exhaust outlet 34 isadapted for connection to the exhaust system in the plant or building inwhich the work station is located, so as to provide a vacuum exhaustwhich will be applied to the work modules 18, 20, 22, 24, 26, 28, 30, aswill be explained hereinafter.

Referring now to FIG. 2, the work station frame and air supply unit areshown. Extending transversely across the lower portion of the workstation frame 12 is a common exhaust plenum 36, which empties into theexhaust outlet 34. As is seen in FIG. 2, the work station frame 12consists of a pair of L-shaped legs 38 which support the air supply unit14. A rear wall 40 is attached between the legs 38 above the commonexhaust plenum 36.

In FIG. 3, the module stand 32 and the work modules are shown as removedfrom the work station frame 12. Also, the work module 22 has beenremoved from the module stand 32 to better illustrate the disposition ofthe work modules on the stand.

FIG. 4 illustrates, in greater detail, the structure of the work stationframe 12. In FIG. 4, a utilities panel 40 is supported from one of thelegs 38. The panel 40 contains an array of couplings 42 which extendthrough the panel 40 to control valves (not shown). The control valvesare, in turn, connectedto the utility supply lines in the plant wherethe work station is located. For example, in addition to an electricaloutlet 44, the utilities panel 40 may supply nitrogen, a source ofvacuum, city water, and distilled water at the couplings 42. Also seenin FIG. 4 is a drain outlet 46 which is connected to the common exhaustplenum 36.

FIG. 5 is a sectional view of the air supply unit 14. An exhaust blower48 functions to draw air through the prefilter 16 into the interior ofthe air supply unit 14. The air then passes through a high efficiencyparticulate air filter unit (HEPA filter) 50. The HEPA filter 50 issupported within the air supply unit 14by a bracket assembly 52 so as tobe readily removable for changing or replacement. I-IEPA filters aredescribed in TID7023, a publication of the U. 8. Atomic EnergyCommission. The air, after passing through the HEPA filter, passes outthe lower portion of the air supply unit through a grating 54. Airsupply units, such as that shown in FIG. 5, are well known in the art.

In FIG. 6, there is shown one of the work modules in place in the workstation. The particular work module 22 shown in FIG. 6 is a wash basin.As will be seen, the wash basin work module 22 is supported, at itsfront, by the module stand 32 and, at its rear, by the common exhaustplenum 36. The common exhaust plenum 36 may be made of any appropriatematerial, such as polypropylene, and includes a flat upper surface 56,to which the exhaust outlet 34 is attached so as to open into the commonexhaust plenum 36. The common exhaust plenum 36 also has a slopingbottom surface 58 20 and a drain fitting 60 at the lower most portionthereof.

The drain fittings 60 has the drain outlet 46 attached thereto (see FIG.4). In the exhaust outlet 34, a master damper control 62 providesoverall control of the amount of vacuum which is applied to the commonex- 25 haust plenum 36. This master damper control permits the vacuumapplied to the work station from the vacuum supply available in theplant to be reduced to about one inch of water, which is sufficientvacuum for the operation of the work bench of the present inven- 30tion.

FIG. 7 is a view in section of the wash basin module 22 shown in FIG. 6.As will be seen in FIG. 7, the module 22 is constructed in the shape ofa generally 66, and a flat upper surface 68. The fiat upper surface 68has a work receiving opening 70 formed therein. At the front of the workmodule 22, a lower front plate 72 is connected to the bottom 64 and acontrol panel 74 is 40 connected to the flatupper surface 68. Theenclosure is completed by the support plate 76 which rests upon themodule stand 32 (see FIG. 6). Disposed in the generally hollow interiorof the work module 22 is a sink 78 having drain holes 80 toward the rearthereof.

45 A water inlet pipe 82 extends through the bottom 64 and is fixed inplace by a support sleeve 84. A ball valve 86 is disposed between thewater inlet pipe 82 and a goose neck 88 so as to control the flow ofwater from the water inlet pipe through the goose neck into the 50 sink.A valve actuator stem 90 extends between the ball valve 86 and a valveactuator knob 92. The knob is turned to open or close the ball valve asappropriate. The goose neck 88 is mounted by means of a boss 94 to theflat upper surface 68.

55 A module exhaust plenum 96 is formed within the module 22 between thesink 78 and the back side 66. The module exhaust plenum 96 has a moduledamper 98 mounted on a module damper control 100 by means of a mountingsleeve 102, to which the module damper 98 is attached, and whichthreadably engages a threaded portion 104 of the module damper control.The module damper control 100 terminates, at each end, in pins 106 and108, respectively. The pin 106 extends through an aperture in a mountingplate 110 which is fastened between a pair of rectangular plates 112,114 attached to the bottom 64 of the module 22. A pair of end plates116, only one of which is shown in rectangular box by means of a bottom64, a back side FIG. 7, together with the rectangular plates 112, 114,form an outlet for the module exhaust plenum, opening into the inletportion of the common exhaust plenum 36. The common exhaust plenum, atits inlet has a pair of exhaust inlet forming side plates 118, 120,which are shown in greater detail in FIG. 6, and serve to support therear portion of the module 22. The pin 108 on the module damper control100 extends through an aperture 122 formed in the flat upper surface 68.Thus, the pins 106, 108 fix the position of the module damper control100 while permitting rotation of the damper control to raise or lowerthe damper 98. To this end, the pin 108 has a recess formed in theextremity thereof for receiving a screwdriver blade to facilitaterotation of the damper control 100.

As will be seen in FIG. 7, the sink 78 is of a size somewhat greaterthan the work receiving opening 70, as the sink has walls 126 formedwithin the module and below and recessed from the periphery of the workreceiving opening, so that the opening forms an overhanging lip 128about the sink walls. In the sink 78, immediately below the uppersurface 68, there are formed a series of apertures 124 extending throughthe walls 126.

FIG. 8 is a sectional view of the work module 22 taken along lines 8-8of FIG. 7, illustrating the manner by which the module damper 98 isdisposed within the module 22. Opposite the module damper control 100,the damper 98 rests against the bottom 64 and is held in this positionby means of a pivot block 130. The module 22 has a pair of side walls132, to one of which the pivot block is attached. Thus, the moduledamper 98 may move vertically along the module damper control 100 whilebeing restrained from other than pivotal movement at its opposite end bythe pivot block 130.

FIG. 9 is a view, in section, of another embodiment of work module,illustrating, the work module 20, which is a module particularly adaptedfor boiling concentrated acid and the like. The work module has a backwall and module damper construction the same as that shown in FIGS. 7and 8 with respect to the work module 22. The work module 20 has a flatupper surface 138. The flat upper surface 138 has two access openings140, 142 formed therewithin. The openings are circular in configuration.Within the module 20, a pair of glass beakers 144 rests upon heaterelements 146. The heater elements 146 are separated from a heater baseframe 148 by insulation 150. The sides of the beakers 144 are enclosedby insulation 152. Electrical leads 154 connect the heating elements 146to a control switch 156 mounted on a control panel 158 of the workmodule 20. The heater base frame is supported from the flat uppersurface 138 by a bracket (not shown). Beneath each of the accessopenings 140, 142 is a cylindrical wall 160, 162, respectively,extending into the interior of the module from the flat upper surface138. These cylindrical walls 160, 162 each have a plurality of apertures164 formed therein in horizontal alignment.

In the embodiment of work module shown in FIG. 9, the overhanging lipabout the cylindrical walls 160, 162 is formed by means of an uppersurface cover plate 166 having work receiving openings 168, 170 formedtherein so as to be disposed over the heating elements 146. In thisembodiment,'a depending flange 172, 174 is formed about each of the workreceiving openings 168, 170 and extending into the hollow interior ofthe work module 20. The depending flanges terminate short of thehorizontal alignment of apertures 64.

The use and operation of the clean work station of the present inventionwill now be described. First, the determination is made as to the typeof work to be carried out in the module. From this determination, theparticular work modules, as to facilities to be provided, can beselected. The individual modules are then installed in the station frame12, so as to form an array of modules such as that seen in FIG. 1.Obviously, in place of any one of the work modules 18, 20, 22, 24, 26,28, 30 of FIG. 1, a blank work module, that is, a module having a flatsolid upper face with no provision for utilities, may be substituted.Such may be desirable where additional working surface is to beprovided. Additionally, the use of blank work modules, rather thanfunctioning work modules, will reduce the exhaust requirements for theclean work station 10 without the necessity of completely enclosing themodule exhaust dampers for work modules not being utilized in theparticular operation.

When the work modules have been inserted in the desired array in thework station frame 12, appropriate connections are made between theindividual work modules and the utilities panel 40. Electricalconnections are made by using appropriate insulated wire. Vacuum andfluid supply lines, of conventional flexible construction, are utilizedto make the appropriate gas or liquid connections between the couplings42 and the individual couplings on each of the work modules. Theutilities panel control valves are then opened to supply the utilitiesto the individual control valves on the work modules.

The exhaust applied to each module is controlled, by means of the masterdamper control 62 to provide, in the common exhaust plenum 36, a minimumexhaust which exceeds the maximum exhaust pressure required by any ofthe work modules. The common exhaust plenum is then applied to the workmodules and the individual ones of the work modules are adjusted, as toactual exhaust utilized, as appropriate to insure that the exhaustrequirements of the work to be carried on at the module are met, withoututilizing excessive exhaust. By such an individual module exhaustcontrol, it has been found that the exhaust requirements of the workstation are reduced a minimum of percent.

Typical dimensions for a work module are 11 inches in depth, 27 inchesin length and, for the sink work module 24, 24 inches in width, and 12inches width for the hot plate module 22. The horizontal alignment ofapertures is about 0.75 inches below the flat upper surface of the workmodule. The overhanging lip is at least 0.75 inches and, if thedepending flange is not utilized, should be about 1 inch. The exhaustapertures may typically be one-fourth inch diameter holes. However, aswill be obvious, rather than utilizing a plurality of separate holes, aslit-type of exhaust aperture can be utilized, which is, in actuality,an infinite number of holes. Thus, as used herein, the term plurality ofapertures" comprehends both separate, individually spaced circular crosssection apertures, apertures of the slit or elongated rectangle type andother obvious varients.

The total volume of the apertures in a given module determines, with theexhaust pressure, the volume of air which is exhausted through theparticular module. As it is desirable to reduce this volume of airexhausted, it is preferable to reduce the total area of exhaustapertures to that minimum area which provides for sufficient exhaust. Aswill be apparent from the foregoing, if, in a given application, thequantity of air exhausted utilizing the preferred 1 inch of water staticpressure at the common exhaust plenum, does not provide sufficientexhaust, the quantity of air exhausted can also be increased byincreasing the area of the exhaust apertures in the module.

In operation, typical characteristics for the hot plate module 20,utilizing an exhaust pressure of 1 inch of water at the common exhaustplenum 36, would be there between 0.25 and 0.4 inches exhaust at theapertures 124, an exhaust rate of about 22 cubic feet per minute, and anexhaust velocity through the apertures of about 1,300 feet per minute.Corresponding typical characteristics for the sink module 22 would be1,500 feet per minute exhaust velocity and 42 cubic feet per minuteexhaust volume.

It should be understood that the laminar flow air .supply to the cleanwork station according to the present invention is not necessarilyreduced. Rather, the reduction occurs in the quantity of air required tobe exhausted through the work station exhaust system. Thus, in aparticular work module array in which a 75 percent reduction on airexhausted occurs, the air which would have been exhausted inconventional devices but is not required to be exhausted by reason ofthe present invention, passes out from the work station into the generalsurrounding atmosphere. Such air then recycles through the air supply ofthe work station, nor- 'mally resulting, since the air has already beenfiltered, in prolonged life of the work station filter units.

Many conventional devices require the exhaust system, in order to avoidthe spread of noxious fumes and the like into the surroundingatmosphere, to aspirate air from the surrounding atmosphere into theexhaust system directly, which type of operation is contrary to FederalStandard 209a. The clean work station of the present invention functionsin accordance with the flow diagram of FIG. 8 of said Standard,providing a true laminar flow clean work station in accordance withparagraph 40.3.5 of said Standard, i.e., without outside air beingaspirated into the work area. The improved exhaust performance of thepresent invention is accomplished by the combination of the workreceiving opening, the array of exhaust outlets disposed below the workreceiving opening and baffled from the work receiving opening by theoverhanging lip and, when desired, the depending flange. Noxious fumes,and the like, which exist in the work module are contained below thework receiving opening, and are exhausted through the lip exhaust,rather than rising through the work receiving opening so as to escapeinto the surrounding atmosphere. Since the lip exhaust removes only asmall percentage of the laminar flow air supplied, the exhaustrequirement of the work station is greatly reduced from that ofconventional devices, in which the work is carried on directly on theupper surtion to avoid diffusion of the noxious gasses.

The invention claimed is:

1. in a clean work station, the combination of:

a work station frame;

at least one work module having 1. a generally flat upper surface;

2. a hollow interior;

3. a module exhaust plenum communicating with the hollow interior;

4. an adjustable damper control for said module exhaust plenum; and

5. means forming a work receiving opening in the upper surface;

a common exhaust plenum attached to the frame;

means connecting each module exhaust plenum to the common exhaustplenum, whereby the module damper control controls the flow of air fromthe hollow interior of the work module to the common exhaust plenum;

wall means formed within said module and below and recessed from theperiphery of the work receiving opening so that the opening forms anoverhanging lip about said wall means; and

a plurality of apertures formed in said wall means and disposed inhorizontal alignment immediately below said overhanging lip.

2. The combination of claim 1, and including a master damper control andmeans connecting said master damper control to the common exhaust plenumfor controlling vacuum applied to the common exhaust plenum.

3. The combination of claim 1 and in which the overhanging lip has adepending flange attached thereto, said flange terminating short of theaperture alignment.

4. The combination of claim 1, and in which the apertures are-alignedapproximately 0.75 inches below the upper surface of the module at thework receiving opening.

5. The combination of claim 1, and in which the overhanging lipoverhangs the wall forming means by at least 0.75 inches.

6. The combination of claim 3, and in which the overhanging lipoverhangs the wall forming means by approximately 1 inch, the aperturesare aligned approximately 0.75 inches below the module upper surface,and the depending flange terminates approximately 0.25 inches above theaperture alignment.

7. The combination of claim 4, and in which the overhanging lipoverhangs the wall forming means by at least 0.75 inches.

8. The combination of claim 6, and including a master damper control andmeans connecting said master damper control to the common exhaust plenumfor controlling vacuum applied to the common exhaust plenum.

9. The combination of claim 7, and including a master damper control andmeans connecting said master damper control to the common exhaust plenumfor controlling vacuum applied to the common exhaust plenum.

1. In a clean work station, the combination of: a work station frame; atleast one work module having
 1. a generally flat upper surface;
 1. In aclean work station, the combination of: a work station frame; at leastone work module having
 1. a generally flat upper surface;
 2. a hollowinterior;
 3. a module exhaust plenum communicating with the hollowinterior;
 4. an adjustable damper control for said module exhaustplenum; and
 5. means forming a work receiving opening in the uppersurface; a common exhaust plenum attached to the frame; means connectingeach module exhaust plenum to the common exhaust plenum, whereby themodule damper control controls the flow of air from the hollow interiorof the work module to the common exhaust plenum; wall means formedwithin said module and below and recessed from the periphery of the workreceiving opening so that the opening forms an overhanging lip aboutsaid wall means; and a plurality of apertures formed in said wall meansand disposed in horizontal alignment immediately below said overhanginglip.
 2. a hollow interior;
 2. The combination of claim 1, and includinga master damper control and means connecting said master damper controlto the common exhaust plenum for controlling vacuum applied to thecommon exhaust plenum.
 3. The combination of claim 1 and in which theoverhanging lip has a depending flange attached thereto, said flangeterminating short of the aperture alignment.
 3. a module exhaust plenumcommunicating with the hollow interior;
 4. an adjustable damper controlfor said module exhaust plenum; and
 4. The combination of claim 1, andin which the apertures are aligned approximately 0.75 inches below theupper surface of the module at the work receiving opening.
 5. Thecombination of claim 1, and in which the overhanging lip overhangs thewall forming means by at least 0.75 inches.
 5. means forming a workreceiving opening in the upper surface; a common exhaust plenum attachedto the frame; means connecting each module exhaust plenum to the commonexhaust plenum, whereby the module damper control controls the flow ofair from the hollow interior of the work module to the common exhaustplenum; wall means formed within said module and below and recessed fromthe periphery of the work receiving opening so that the opening forms anoverhanging lip about said wall means; and a plurality of aperturesformed in said wall means and disposed in horizontal alignmentimmediately below said overhanging lip.
 6. The combination of claim 3,and in which the overhanging lip overhangs the wall forming means byapproximately 1 inch, the apertures are aligned approximately 0.75inches below the module upper surface, and the depending flangeterminates approximately 0.25 inches above the aperture alignment. 7.The combination of claim 4, and in which the overhanging lip overhangsthe wall forming means by at least 0.75 inches.
 8. The combination ofclaim 6, and including a master damper control and means connecting saidmaster damper control to the common exhaust plenum for controllingvacuum applied to the common exhaust plenum.